Encryption and decryption key arrangements

摘要

An apparatus, arranged to encrypt or decrypt messages, is arranged to generate a session key of a variable selected number of characters and to distribute these characters in sequence into a predetermined number of groups to form a corresponding number of primitives: these primitives are used, in accordance with a predetermined algorithm, to form a cypher key stream the characters of which are used in sequence to encrypt or decrypt successive characters (or elements) of a message.